Hydraulic operating mechanism for circuit breakers and the like



March 2, 1937. I J w. R 2,072,481

HYDRAULIC OPERATING MECHANISM FOR CIRCUIT BREAKERS AND THE LIKE FiledJan. 27, 1934 Inventor:

Jacob W.mCT|aiTi b3 77 H is tow-neg- Patente cl Mar. 2, 1937 I UNITEDSTATES PATENT OFFICE HYDRAULIC OPERATi KTG DIECHANISM FOR CIRCUITBREAKERS AND THE LIKE Jacob W. McNair Erie, Pm, assignor to GeneralElectric Company, a corporation 01' New York Application January 27,1934, Serial No. 708,637 6-Claims. (01-60-52) My invention relates tohydraulic operating 20 in which is mounted a tripping coil orbuckingmechanisms for circuit breakers and the like and bar (not shown)arranged to shift the magnetic has for an object the provision of asimple, posiflux from the armature Hi to permit the opening tive-actinghydraulic mechanism for resetting a of the circuit breaker.

circuit breaker after it has been tripped. Circuit breakers of thisgeneral character are 5 In applying an hydraulic operator to circuitdesigned to carry currents of large magnitude, breakers of the trip-freetype it is desirable to the parts being relatively heavy to provideadeprovide means permitting a quick return of the quate current carryingcapacity. Consequently hydraulic operator after the circuit closingoperain order to insure the high speed opening of the 10 tion has beeninitiated so that the circuit breaker circuit breaker, a large amount ofenergy is 10 will be free to open its contacts immediately in stored inthe opening spring l4 during the circuit case of overload. Furthermore,the ordinary byclosing operation, The spring I4 ofcourse prepass valvesheretofore used on hydraulic operasents a substantial amount ofresistance to the tors do not permit a quick retraction of the hyclosingoperation. I have found it desirable to draulic operating mechanism andfurthermore provide a gear pump hydraulic closing device 22 are notsuificiently positive in operation to be to close the circuit breakeragainst the strong I reliable under all conditions of operation. bias ofthe opening spring. The circuit breaker In carrying out my invention inone form ii] is trip-free, that is to say it cannot be held in thereof Iprovide a gear pump arranged to apply the closed circuit positionbyineans of the operpressure to a switch-operating piston, theoperaating member or hydraulic closing means 22, the 20 tion of acontrolling by-pass valve being accomtrip-free feature being provided bya closing plished in response to pressure developed by the spring 22connected to a switch member 25 Pump. The hy-pass valve is of relativelylarge pivotedat 26 and to which is pivoted at 22 the. diameter and isnormally biased to its open posimovable contact member l2.

25 tion by means of a compression spring. In closing In order to closethe circuit breaker with the 25 the circuit breaker the gear pump motoris enerparts in the positions shown an electric motor 34 ized to driveliquid against the face of the byis energized and operates the gear pumpclosing pass valve to move it to a closed position. to transmeans 22 tomove a plunger 36 againstthe roller fer the flow of fluid to theoperating piston. A. 29, mounted by means of a pin 20 in the divided 30further feature of the invention is the provision end 22 of the switchmember 25. As the plunger of a relatively small opening in the face ofthe 3t rises it moves the end 32 of the switch member by-pass valve sothat a minimum resistance is 25 in a clockwise direction around itspivot 2t, encounteredv in the movement of the valve from thereby movingthe movable contact i2 a predethe closed position to the open positionwith retermined distance towards the circuit closing posi- 35 spect tothe by-pass passageway. tion. A link 22 connected to the movable con- 35For a' more complete understanding of my intact member I12 and to oneend W of the armature vention, reference should be had to the accomitcauses the armature pivoted at 22 to be rotated panying drawing whereinI have shown diagramin a counter-clockwise direction into engagementmatically in Fig. 1 my invention applied to a cirwith the holding magnetit. At this time the 40 cult breaker; Fig. 2 is an elevation, partly insec-- operating coil M of the holding magnet it is'ener- 40 tion, of thegear pump; Fig. 3 diagrammatically gized and maintains the armature itagainst the illustrates the hydraulic system of the gear pump magnet.The opening spring i l and the closing of Fig. 2; Fig. 4 is a sectionalelevation taken on spring 22 are under a maximum amount of tenthe linesll of Fig. 2, and Fig. 5 is a sectional sion. As soon as the armature itis operated into v 15 elevation taken on the lines 5--5 of Fig. 2.engagement with the electromagnet the motor 22 Referring to the drawing,I have shown my inis deenergized and the closing means 22 autovention inone form as applied to a circuit breaker matically retracts the plunger26 in a very short it provided with a stationary contact M and ainterval of time. i As the plunger 22 moves downmovable contact W. Themovable contact i2 is wardly the closing spring 22 rotates the switch S0normally biased to the open circuit position by member 25 in acounter-clockwise direction, one

means of a strong opening spring M, a holding end 48 of the connectinglink 39 thereupon promagnet it being arranged to cooperate with anviding a pivot point for the movable contact memarmature it to hold thecircuit breaker in the her l2 so that the movable contact'member l2closed circuit position. It will be observed that is rotated in aclockwise direction into engagei5 the electromagnet i6 is provided withan air gap ment with the stationary contact H Referring to Figs. 2 and3, the operation of the closing means 22 will now be described in detailand it will be apparent how I accomplish the positive operation of thehydraulic operator and provide for a quick retraction of .the plunger 36after the circuit closing operation has been completed.

As soon as the motor 34 is energized the gears 59 of a gear pump 52 arerotated in a direction to transfer oil or a similar liquid from areservoir which comprises the upper side 53 of a piston 54 secured toone end 55 of a rod 56 connected to the plunger 36. The movement of thepiston 54 is not greater than the cylinder guide wall 53a, the upper endof which surface terminates adjacent an enlarged portion 53b of thecylinder. The enlarged portion 53b permits the insertion of a cylinderboring tool for the machining of the cylinder guide wall without thenecessity of machining the entire inner surface of the device 22.Furthermore, a slightly larger oil storage space is provided by thisenlarged portion 53b. The

upper end 22a of the cylinder is provided with threaded holes 56 toreceive threaded bolts 58a which serve to secure the cylinder head 22bto the cylinder.

Continuing with the operation of my invention, the flow of oil from thegear pump is conducted through the conduit 51 to theface 59 of a bypassvalve 60 which is biased to its open position by a compression spring6|. As the pressure builds up on the face 59 of the by-pass valve 60 itis operated against the bias of the spring 6| until it closes the upperhalf of a conduit 64 extending between the upper side 53 of the piston54 and a chamber having a movable wall comprising the lower side 66 ofthe piston 54. The lower half 64? of the conduit is offset with respectto the upper half 64a so that the valve when in its closed positionconnects the lower half of the conduit 64 to the conduit 51. A groove51a is provided to insure adequate room for the flow oil.

By operating the valve directly with the output from the gear pump anytendency for the valve 60 to stick is overcome, since in that event thepressure would be gradually built up by the gear pump 52 on the valueuntil it is operated. It will be understood by those skilled in the artthat the pressure built up by the gear pump may be of the order ofseveral hundred pounds per square inch which, of course, would be morethan ample to free the valve 65 from the worst possible case of stickingthat might be encountered.

Continuing with the operation of my invention, as soon as the by-passvalve 66 is operated to close the conduit 64 the output of the gear pump51 will be applied to the lower side 65 of the piston 54. The flow ofoil from the gear pump is by way of conduit 51, groove 51a, and thelower half of conduit 64. The groove 51a insures an unrestricted flow'ofoil to the lower side 65 of the piston. The pressure built up by theflow of oil moves the piston 54 gradually and positively upward againstthe bias of a retracting spring 66, the plunger 36 engaging the roller29 to initiate the closing of the circuit breaker l0. i

As soon as the piston 54 has been operated to its uppermost positioncorresponding to the time the armature l3 has been moved against theelectromagnet Hi, the motor 34 is deenergized and quickly comes to astandstill. As soon as the gears 50 and I. of the gear pump stop, thepres-.

sure exerted against the face 9of the by-pass valve 65 drops to zero andthespring 6i operates the valve to the position shown in Fig. 2. Inorder to minimize the resistance of the valve face 59 against the headof oil, an aperture is proof relatively large diameter, permits arelatively large volume of oil to flow immediately from the lower side65 of the piston 54 to the upper side 53, thereby permitting theretracting spring 66 to operate quickly the piston to the position shownin Fig. 2. In actual operation I have found that in a typicalinstallation the hydraulic pump operated the plunger 36 to its outermostposition in approximately two seconds and permitted the retraction ofthe plunger 36 in substantially one half second, this time for thesequence of operations being entirely satisfactory for the closing ofthe circuit breaker l0.

While I have shown a particular embodiment of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemany modifications may be made, and I, therefore, contemplate by theappended claims to cover any such modifications as fall within the truespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

1. An hydraulic operating mechanism comprising a housing containing aliquid, a gear pump mounted in said housing, an operating piston, apassageway extending between the upper and lower sides of said piston, aby-pass valve in said passageway normally biased to its open positionfor the flow of liquid through said passageway, means for directing theliquid from said pump against said valve so that the fluid pressuredeveloped by said gear pump acts directly on said valve to operate it toits closed position to close said passageway, an opening being providedaround said valve for the flow of said liquid against one face of saidpiston, and means for decreasing the fluid resistance of said valve forinsuring a rapid movement of said valve when operated from said closedposition to said open position.

. 2. An hydraulic operating mechanism, comprising a housing containingaliquid, a piston mounted in said housing, a gear pump, a passagewayconnecting the upper and lower sides of said piston, a by-pass valveoperable from an open position to a closed position to prevent the flowof liquid from one side of the piston to the other, a conduit connectingone side of said gear pump to the upper side of said piston, 'and asecond conduit connecting said gear pump to said bypass valve, the flowof liquid from said gearv pump being applied directly to said by-passvalve to operate it from its open position to its closed position, saidvalve when in said closed position connecting said second conduit tosaid passageway for the flow of liquid to the lower side of said piston.a

3, An hydraulic mechanism comprising a housing containing a liquid, apiston mounted in said housing for movement between predeterminedpositions, a conduit of relatively large cross sectional area extendingbetween the upper and lower portions of said housing above and below thesaid predetermined positions of said piston, a by-pass valve normallybiased to an open position and arranged to be operated to a closedposition to prevent the flow of fluid between the upper and lower sidesof said piston, a gear pump, connecting the upper and duits connectingthe output side 01' said gear pump to one face oi said valve and theinput side of said gear pump to said upper portion of said housing, theoperation of said gear pump thereby i'orcing liquid against said by-passvalve to operate positively said valve to said closed position, saidvalve when in said closed position permitting the flow of liquid fromsaid pump to the lower side of said piston, and means biasing saidpiston to its lowermost position whereby said piston is returned to saidlower position as soon as said pressure on said by-pass valve decreasessuiliciently to permit itsbiasing means to operate said valve from saidclosed position to said open position. 4

4. An hydraulic operating mechanism comprising a housing containingaliquid, a piston slidably mounted in said housing, a passageway conlowersides of said piston, a gear pump, a conduit connecting one side of saidpump to said upper side of said piston to receive oil therefrom, asecond conduit connecting the other side or said gear pump to saidpassageway intermediate the ends thereof for the delivery of liquidthereto, a by-pass valve slidably mounted for movement between open andclosed positions, biasing means for biasing said valve to said openposition, said valve when in said open position being operable to saidclosed position by the flow of liquid from said second conduit, saidvalve when in said closed position connecting said secand conduit tothat part of said passageway connect-ed is said lower side of saidpiston and closing that portion of said passageway connected to saidupper side oi said piston.

5. an hydraulic operator comprising a liquid filled chamber having amovable wall. a reservoir,

a passageway extending between said chamber Said reservoir, a by-passvalve in said pasto operate it to its closed sageway normally biased toits open position to permit theflow of liquid through. said passageway,pumping means connected to said reservoir, means for directing theliquid from said pumping means against said valve so that the pressuredeveloped by said pump'acts directly on said valve position and therebyclose said passageway, Sa d valve when in said closed position providingfor the flow of said liquid into said chamber to move said wall, and

means for decreasing the fluid resistance of said valve for insuring arapid return movement of said valve from said closed position to saidopen position upon a predetermined decrease in the pressure supplied bysaid pumping means.

6. An hydraulic operator comprising a liquid filled chamber having amovable wall, a reservoir, a' passageway extending between said chamberand said reservoir, 9, by-pass valve insaid passageway normally biasedto its open position to permit the flow of liquid through saidpassageway, pumping means connected to said reservoir, means fordirecting the liquid irom said pumping means against a face of saidvalve so that the pressure developed by said pumping means acts directlyon said valve to operate it to its closed position and thereby closesaid eway, said valve when in said closed position providing for theflow of liquid into said chamber to move said wall, and means includingan aperture in saidvalve race for minimizing the liquid resistance tomovement or said valve from said closed to said open position to insurea rapid return movement of said valve upon a predetermined decrease inthe pressure supplied by said pumping means, the size of said aperturebeing insumcient to pre vent the building up of pressure on said valveface by said pumping means.

. JACOB W. McNAIRY.

